Meniscus Gene Expression Profiling: Inner and Outer Zone Tissue Comparison to Cartilage and Passaged Monolayer Meniscus Cells
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ABSTRACT: Meniscus injuries are common and while surgical strategies have improved, there is a need for alternative therapeutics to improve long-term outcomes and prevent post-traumatic osteoarthritis. Current research efforts in regenerative therapies and tissue engineering are hindered by a lack of understanding of meniscus cell biology and a poorly defined meniscus cell phenotype. This study utilized bulk RNA-sequencing to identify unique and overlapping transcriptomic profiles in cartilage, inner and outer zone meniscus tissue, and passaged inner and outer zone meniscus cells. The greatest transcriptomic differences were identified when comparing meniscus tissue to monolayer cultured cells (> 4,600 differentially expressed genes (DEGs)) and meniscus tissue to cartilage (> 3,100 DEGs). While zonal differences exist within the meniscus tissue (205 DEGs between inner and outer zone meniscus tissue), meniscus resident cells are more similar to each other than to either cartilage or monolayer meniscus cells. Additionally, we identified and validated LUM and PRRX1 as potential markers for meniscus tissue and ACTA2, FSTL1, SFRP2, and TAGLN as novel markers for meniscus cell dedifferentiation. Our data contribute significantly to the current characterization of meniscus cells and provide an important foundation for future work in meniscus cell biology, regenerative medicine, and tissue engineering.
Project description:Meniscus injuries are highly prevalent and are linked to the development of post-traumatic osteoarthritis (PTOA). The inflammatory cytokine IL-1 is elevated in synovial fluid following knee injuries, causes degradation of meniscus tissue, and inhibits meniscus repair. Dynamic mechanical compression of meniscus tissue has been shown to improve integrative repair in the presence of IL-1; however, there remains a dearth of knowledge on global effects of loading on meniscus cell phenotype and transcriptomic profiles. In this study, we performed mRNA-Seq on meniscus tissue explants from inner and outer zone regions of porcine menisci subjected to dynamic compression in the presence and absence of IL-1 to identify cellular responses to mechanical load, identify differences in response to load based on zonal characteristics, and identify IL-1 induced inflammatory responses modulated by load.
Project description:Meniscus injuries are highly prevalent and are linked to the development of post-traumatic osteoarthritis (PTOA). The inflammatory cytokine IL-1 is elevated in synovial fluid following knee injuries, causes degradation of meniscus tissue, and inhibits meniscus repair. Cyclic tensile stretch has been shown to modulate the expression of pro-inflammatory cytokines and degradative enzymes induced by IL-1; however, there remains a dearth of knowledge on global effects of loading on meniscus cell phenotype and transcriptomic profiles. In this study, we performed mRNA-Seq on meniscus cells isolated from inner and outer zone regions of porcine menisci subjected to cyclic tensile strain in the presence and absence of IL-1 to identify cellular responses to mechanical load, identify differences in response to load based on zonal characteristics, and identify IL-1 induced inflammatory responses modulated by load.
Project description:Analysis of gene expression in E16 mouse meniscus, articular cartilage, and cruciate ligaments Limbs were dissected from E16 CD-1 mice. Samples were frozen in OCT and cryosectioned. Meniscus, articular carilage, and cruciate ligament were isolated using laser capture microdissection. Total RNA was isolated from these tissues, amplified, and gene expression was analyzed using microarrays. Three biological replicates were analyzed for each tissue type. Total RNA extracted from E16 mouse meniscus, articular cartilage, and cruciate ligaments
Project description:The meniscus consists of two zones red-red (outer) and white-white (inner). We used single cell RNA-seq to analyze the differences in the composition of cell types between zones. We also compared the medial and lateral meniscus.
Project description:This study investigates the transcriptome response of meniscus fibrochondrocytes (MFCs) to the low oxygen and mechanical loading signals experienced in the knee joint using a model system. We hypothesized that short term exposure to the combined treatment would promote a matrix-forming phenotype supportive of inner meniscus tissue formation. Human MFCs on a collagen scaffold were stimulated to form fibrocartilage over 6weeks under normoxic (NRX, 20% O2) conditions with supplemented TGF -β3. Tissues experienced a delayed 24h hypoxia treatment (HYP, 3% O2) and then 5min of dynamic compression (DC) between 30 and 40% strain. Delayed HYP induced an anabolic and anti-catabolic expression profile for hyaline cartilage matrix markers, while DC induced an inflammatory matrix remodeling response along with upregulation of both SOX9 and COL1A1. There were 41 genes regulated by both HYP and DC. Overall, the combined treatment supported a unique gene expression profile favouring the hyaline cartilage aspect of inner meniscus matrix and matrix remodeling.
Project description:Background: Meniscus tears are the most common injury in the knee and are associated with an increased risk of osteoarthritis (OA). The molecular profile of knees with meniscus tears is not well-studied. Therefore, to advance our understanding of the early response of the knee to injury, we compared the gene expression profile of meniscus and articular cartilage within the same knees following meniscus injury. Hypothesis/Purpose: To identify differences between the molecular signatures of meniscus and articular cartilage from knees with intact articular cartilage undergoing arthroscopic partial meniscectomy. Study Design: Descriptive laboratory study Methods: Patients (n=12) with a known isolated medial meniscus tear without any knee chondrosis or radiographic OA were consented prior to surgery. During arthroscopic partial meniscectomy, a sample of their injured meniscus and a sample of their articular cartilage off the medial femoral condyle were procured. The transcriptome signatures, as measured through Affymetrix microarray, were compared between the two tissues and underlying biological processes were explored computationally. Results: 3566 gene transcripts were differentially expressed between meniscus and articular cartilage. Gene transcripts down-regulated in articular cartilage were associated with extracellular matrix organization, wound healing, cell adhesion, and chemotaxis. Gene transcripts up-regulated in articular cartilage were associated with blood vessels morphogenesis and angiogenesis. Examples of individual genes with significant differences in expression between the two tissues include IBSP (23.76 fold; P < 0.001), upregulated in meniscus, and TREM1 (3.23 fold; P = 0.006), upregulated in meniscus. Conclusion: The meniscus and articular cartilage have distinct gene expression profiles in knees with meniscus tears and intact articular cartilage. Total RNA obtained from injured meniscus and normal articular cartilage from patients undergoing partial meniscectomy.
Project description:Meniscus fibrochondrocytes (MFCs) experience simultaneous hypoxia and mechanical loading in the knee, conditions that have promising applications in human meniscus tissue engineering. We hypothesized that “mechano-hypoxia conditioning,” using mechanical loading such as dynamic compression (DC) and cyclic hydrostatic pressure (CHP), would enhance development of human meniscus fibrocartilage extracellular matrix in vitro. MFCs from inner human meniscus surgical discards were pre-cultured on porous type I collagen scaffolds with TGF-β3 supplementation to form baseline tissues with newly-formed matrix. They were then treated with DC or CHP under hypoxia (HYP, 3% O2) for 5 days. DC was the more effective load regime, and combined HYP/DC enhanced gene expression of fibrocartilage precursors. The individual treatments of DC and HYP regulated thousands of genes and combined in an overwhelmingly additive rather than synergistic manner. Baseline tissues were then treated with a short course of DC (5 vs 60 minutes, 10-20% vs 30-40% strain) with different pre-culture durations (3 vs 6 weeks). Longer courses of loading had diminishing returns in terms of gene regulation. There was a dose-effect for higher DC strains, whereas outcomes were mixed for different MFC donors in pre-culture durations. Finally, baseline tissues were conditioned for 3 weeks with mechano-hypoxia conditioning to assess mechanical and protein-level outcomes. There were 1.8 to 5.1-fold gains in the dynamic modulus relative to baseline in HYP/DC, but matrix outcomes were equal or inferior to static controls. Long-term mechano-hypoxia conditioning was effective in suppressing hypertrophic markers (e.g., COL10A1 10-fold suppression vs static/normoxia). Applied appropriately, mechano-hypoxia conditioning can support meniscus fibrocartilage development in vitro and may be useful as a strategy for developing non-hypertrophic articular cartilage using mesenchymal stem cells.
Project description:Analysis of gene expression in E16 mouse meniscus, articular cartilage, and cruciate ligaments Limbs were dissected from E16 CD-1 mice. Samples were frozen in OCT and cryosectioned. Meniscus, articular carilage, and cruciate ligament were isolated using laser capture microdissection. Total RNA was isolated from these tissues, amplified, and gene expression was analyzed using microarrays. Three biological replicates were analyzed for each tissue type.
Project description:Background: Meniscus tears are the most common injury in the knee and are associated with an increased risk of osteoarthritis (OA). The molecular profile of knees with meniscus tears is not well-studied. Therefore, to advance our understanding of the early response of the knee to injury, we compared the gene expression profile of meniscus and articular cartilage within the same knees following meniscus injury. Hypothesis/Purpose: To identify differences between the molecular signatures of meniscus and articular cartilage from knees with intact articular cartilage undergoing arthroscopic partial meniscectomy. Study Design: Descriptive laboratory study Methods: Patients (n=12) with a known isolated medial meniscus tear without any knee chondrosis or radiographic OA were consented prior to surgery. During arthroscopic partial meniscectomy, a sample of their injured meniscus and a sample of their articular cartilage off the medial femoral condyle were procured. The transcriptome signatures, as measured through Affymetrix microarray, were compared between the two tissues and underlying biological processes were explored computationally. Results: 3566 gene transcripts were differentially expressed between meniscus and articular cartilage. Gene transcripts down-regulated in articular cartilage were associated with extracellular matrix organization, wound healing, cell adhesion, and chemotaxis. Gene transcripts up-regulated in articular cartilage were associated with blood vessels morphogenesis and angiogenesis. Examples of individual genes with significant differences in expression between the two tissues include IBSP (23.76 fold; P < 0.001), upregulated in meniscus, and TREM1 (3.23 fold; P = 0.006), upregulated in meniscus. Conclusion: The meniscus and articular cartilage have distinct gene expression profiles in knees with meniscus tears and intact articular cartilage.